特细砂对素混凝土龄期强度的影响

以孟加拉吉大港工程采用特细砂配制的混凝土为研究对象，研究砂率、砂的细度模数、减水剂掺量等因素对素混凝土的龄期强度影响。结果表明，特细砂配制的素混凝土强度随龄期呈现先快速增大后缓慢增大的趋势，3 d强度达到28 d强度的55%以上，7 d强度达到28 d强度的70%以上；小幅度提高砂率对龄期强度影响不大；中砂较特细砂配制的素混凝土28 d强度有小幅提高；减水剂掺量超过1%时，28 d强度有大幅提高。

Influence of ultra-fine sand on age strength of plain concrete

Taking the ultra-fine sand concrete of Chittagong project in Bangladesh as the research object,we study different influencing factors on the age strength of plain concrete,such as the sand ratio,the fineness modulus of sand and the dosage of water reducing agent.The results show that the strength of ultra-fine sand concrete increases rapidly and then increases slowly with the age,3 d strength reaches more than 55% of 28 d strength,7 d strength reaches more than 70% of 28 d strength.The effect of small increase of sand ratio is not significant to the age strength.28 d strength of medium sand concrete is slightly smaller than that of the ultra-fine sand concrete.When the dosage of water reducing agent exceeds 1%,28 d strength is greatly improves.